Electronic products undergo significant reduction in size and weight and extraordinary increase in performance. Such electronic products are represented typically by cellular phones, smartphones, tablet terminals, mobile computers, personal digital assistants (PDAs), and digital still cameras (DSCs). With the technological trend as above, demands are increasingly made to achieve reduction in size, weight, and/or thickness of lenses for use typically in cameras to be mounted to the electronic products.
The lenses are generally produced by a molding (forming) technique using a mold, such as injection molding or cast molding. Known materials for use in lens formation include thermoplastic resins such as polycarbonates; and thermal- or photo-curable resins such as acrylic resins and silicone resins (Patent Literature (PTL) 1 to 4). However, the thermoplastic resins do not have reflow heat resistance, and, for example, camera modules using lenses made from the thermoplastic resins should be assembled in a step different from other parts, and this disadvantageously complicates the production process. In contrast, lenses made from acrylic resins or silicone resins are superior in heat resistance, but are not yet satisfactory in optical properties.